Merged the work by Florian Faber that's distributed separately as
hdspmixer64.
Code taken from http://wiki.linuxproaudio.org/index.php/App:hdspmixer_64
Signed-off-by: Adrian Knoth <adi@drcomp.erfurt.thur.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>